/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/ViewModels/Stack/NiagaraStackFunctionInput.h
Gets a multicast delegate which is called whenever the value on this input changes.
[FOnValueChanged](API\Plugins\NiagaraEditor\ViewModels\Stack\UNiagaraStackFunctionInput\FOnValueChanged) & OnValueChanged()